|I can't recall|
As I was preparing upgrades to the site galleries, I produced a large number of images and put them into a "Potential changes" folder, and over a period of months I would tackle a few new pages at a time, fitting it in around other projects and activities. And now, as I near the end of the new page edits, I find that I can't remember how I achieved this result.
The original was in color, and it's almost certain that I deleted two of the three color channels and then changed contrast... but which channel did I start with? My little experiments haven't produced a match for the result you see here. And of course, that kind of stuff isn't retained in the EXIF info, so while I can tell you what camera, lens, and exposure settings, I can't tell you what editing tricks.
Yet, it was the oblique angle of the light that started it all, even drawing my attention to the American sycamore leaf (Platanus occidentalis,) a great combination of backlighting and shadows thrown by the shape of the leaf itself. What I'm saying it that it isn't too Photoshopped...